Safety and immunogenicity of an intranasal sendai virus-based vaccine for human parainfluenza virus type I and respiratory syncytial virus (SeVRSV) in adults.

SeVRSV is a replication-competent Sendai virus (SeV)-based vaccine carrying the respiratory syncytial virus (RSV) fusion protein (F) gene. Unmanipulated, non-recombinant SeV is a murine parainfluenza virus type 1 (PIV-1) and serves as a Jennerian vaccine for human PIV-1 (hPIV-1). SeV protects African green monkeys (AGM) from infection after hPIV-1 challenge. The recombinant SeVRSV additionally targets RSV and protects AGM from lower respiratory infections after RSV challenge. The present study is the first to report on the safety, viral genome detection, and immunogenicity following SeVRSV vaccination of healthy adults. Seventeen and four healthy adults received intranasal SeVRSV and PBS, respectively, followed by six months of safety monitoring. Virus genome (in nasal wash) and vaccine-specific antibodies (in sera) were monitored for two and four weeks, respectively, post-vaccination. The vaccine was well-tolerated with only mild to moderate reactions that were also present in the placebo group. No severe reactions occurred. As expected, due to preexisting immunity toward hPIV-1 and RSV in adults, vaccine genome detection was transient. There were minimal antibody responses to SeV and negligible responses to RSV F. Results encourage further studies of SeVRSV with progression toward a clinical trial in seronegative children. Abbreviations: AE-adverse event; SAE-serious adverse event; SeV-Sendai virus; RSV-respiratory syncytial virus; PIV-1-parainfluenza virus-type 1; hPIV-1-human parainfluenza virus-type 1; F-RSV fusion protein; SeVRSV-recombinant SeV carrying the RSV F gene; Ab-antibody; MSW-medically significant wheezing; NOCMC-new onset chronic medical condition, mITT-modified Intent to Treat; ALRI-acute lower respiratory tract infection.

Antibody response to influenza infection of mice: different patterns for glycoprotein and nucleocapsid antigens.

Our previous studies of C57BL/6 mice intranasally infected with influenza virus (A/PR8) revealed a spike of virus-specific immunoglobulin A (IgA)-secreting antibody-forming cells (AFC) in the mediastinal lymph node (MLN) 7 days post-infection. Here we show that these AFC are directed only against viral glycoprotein, and not nucleocapsid antigens. The early IgA spike associates with a decline in glycoprotein-specific AFC during week 2 post-infection. In contrast to the glycoprotein-specific AFC, nucleocapsid-specific, IgA-secreting AFC develop gradually in the MLN and persist for more than 3 weeks post-infection. As peripheral lymph node reactions wane, the nucleocapsid-specific AFC appear as long-sustained populations in the bone marrow. Microanatomical examination of the respiratory tract in infected mice shows foci of infection established in the lung 2 days post-infection, from which virus spreads to infect the entire lining of the trachea by day 3. At this time, viral haemagglutinin can be seen within the MLN, probably on projections from infected dendritic cells. This feature disappears within a day, though viral antigen expression continues to spread throughout the respiratory tract. Total IgA- and IgG-secreting AFC appear histologically in large numbers during the first week post-infection, significantly preceding the appearance of germinal centres (revealed by peanut agglutinin staining in week 2). To explain these results, we suggest that the initial immunogenic encounter of B cells with viral antigens occurs about 3 days post-infection in the MLN, with antigens transported by dendritic cells from airway mucosa, the only site of viral replication. Viral glycoproteins expressed as integral membrane components on the surface of infected dendritic cells [probably in the absence of cognate T helper (Th) cells] promote members of expanding relevant B-cell clones to undergo an IgA switch and terminal local plasmacytoid differentiation. Anti-glycoprotein specificities are thus selectively depleted from progeny of activated B-cell clones which are channelled to participate in germinal centre formation (perhaps by cognate T helper cells when they become sufficiently frequent). One product of the germinal centre reaction is the long-sustained, bone marrow-resident population, which is accordingly rich in anti-nucleoprotein, but not anti-glycoprotein specificities. Of note, we find that AFC responses toward influenza virus and Sendai virus differ, even though viral replication is limited to the airway mucosa in each case. The response towards Sendai virus exhibits neither the early appearance of anti-glycoprotein AFC expressing IgA in draining lymph nodes, nor the subsequent relative deficit of this specificity from bone marrow AFC populations.

A five-residue HIV envelope helper T cell determinant: does this peptide-MHC interaction leave the binding groove half empty?

High-resolution structures have revealed major pockets in the MHC class II peptide binding groove within a region designated Pl-P9. The region can accommodate 9-mer peptides, consistent with the observation that minimal core helper T (Th) cell determinants are usually eight or nine residues in size. Here we describe mouse Th cell hybridomas that are specific for a core peptide of only five residues (NPIIL) in the HIV envelope glycoprotein. Effective Th cell stimulation requires that these MHC class II Ia(b)-presented peptides contain amino acids flanking the minimal pentamer, but the flanking residues may be located on either the N or C terminus. To explain these findings, we suggest that mini-Th cell epitopes may effectively associate with MHC when only five (or possibly fewer) of the P1-P9 positions are filled. The remaining positions may be empty, or may be associated with a second, perhaps unrelated, peptide moiety.

Clonal proteomics: one gene - family of proteins.

The work presented here attempts to consolidate our knowledge on cellular transcriptome and proteome. It takes into account that a typical activated cell (lymphocyte) contains 40 000 mRNA molecules at any time, and it represents about 5000 different molecular species of transcripts. Such a cell has about 1 000 000 000 protein molecules, some of them being present at 10 000 000 copies while others at a very low copy number (say 1 to 10 copies per cell). By studying cell free expression of individual cDNA clones (or pools of known complexity) we address to those rare molecular components that will remain undetected by the current analytical means. For our analysis we use cell free translation systems (wheat germ or rabbit reticulocyte origin) and we study polypeptide products originating from intact, or restriction endonuclease-treated cDNA clones. We conclude that in most instances expressed genes yield transcript(s) that translate into several, and often very numerous families of polypeptide species. In our ISODALT two-dimensional gel system we characterize the proteomic profile of the clonal polypeptide families in terms of their molecular mass, charge, multiple products, and appearance.